Fix searching for end of string in python-nav-end-of-statement

* lisp/progmodes/python.el (python-nav-end-of-statement): Add
searching for corresponding string-quote.
* test/lisp/progmodes/python-tests.el (python-nav-end-of-statement-3)
(python-nav-end-of-statement-4, python-info-current-defun-4): New
tests. (Bug#58780)

lisp/progmodes/python.el

@@ -2076,9 +2076,15 @@ of the statement."
                            (goto-char (+ (point)
                                          (python-syntax-count-quotes
                                           (char-after (point)) (point))))
-                           (setq last-string-end
+                           (setq
-                                 (or (re-search-forward
+                            last-string-end
+                            (or (if (eq t (nth 3 (syntax-ppss)))
+                                    (re-search-forward
                                      (rx (syntax string-delimiter)) nil t)
+                                  (ignore-error scan-error
+                                    (goto-char string-start)
+                                    (python-nav--lisp-forward-sexp)
+                                    (point)))
                                 (goto-char (point-max)))))))
                       ((python-syntax-context 'paren)
                        ;; The statement won't end before we've escaped

test/lisp/progmodes/python-tests.el

@@ -2955,6 +2955,36 @@ string
    "'\n''\n"
    (python-nav-end-of-statement)))
 
+(ert-deftest python-nav-end-of-statement-3 ()
+  "Test unmatched quotes (Bug#58780)."
+  (python-tests-with-temp-buffer
+   "
+' \"\"\"
+v = 1
+"
+   (python-tests-look-at "v =")
+   (should (= (save-excursion
+                (python-nav-end-of-statement)
+                (point))
+              (save-excursion
+                (point-max))))))
+
+(ert-deftest python-nav-end-of-statement-4 ()
+  (python-tests-with-temp-buffer
+   "
+abc = 'a\\
+b\\
+c'
+d = '''d'''
+"
+   (python-tests-look-at "b\\")
+   (should (= (save-excursion
+                (python-nav-end-of-statement)
+                (point))
+              (save-excursion
+                (python-tests-look-at "c'")
+                (pos-eol))))))
+
 (ert-deftest python-nav-forward-statement-1 ()
   (python-tests-with-temp-buffer
    "
@@ -5221,6 +5251,20 @@ def decoratorFunctionWithArguments(arg1, arg2, arg3):
    (should (string= (python-info-current-defun t)
                     "def decoratorFunctionWithArguments"))))
 
+(ert-deftest python-info-current-defun-4 ()
+  "Ensure unmatched quotes do not cause hang (Bug#58780)."
+  (python-tests-with-temp-buffer
+   "
+def func():
+    ' \"\"\"
+    v = 1
+"
+   (python-tests-look-at "v = 1")
+   (should (string= (python-info-current-defun)
+                    "func"))
+   (should (string= (python-info-current-defun t)
+                    "def func"))))
+
 (ert-deftest python-info-current-symbol-1 ()
   (python-tests-with-temp-buffer
    "